Its not as isolated as you think. In my club of approximately 60 people, I currently have 5 people learning to fly. On a good day, I'll have 2-3 other people out with me, but its not uncommon for me to be going it alone.

Having said that, I don't care how much work it takes the student, but if I have never done a preflight on the plane, I won't fly it. The first time a student comes to the field, I go over the plane with them from nose to tail, and check everything. Then on subsequent days, I do a more abbreviated pre-flight. It only takes a couple minutes, but its worth it.

Having said that, a few weeks ago i had a student flying a Sig Kadet. I had grounded it two weeks earlier because I didn't like the CG. The following week, one of my other instructors flew it and it was OK. The next week I flew it with the student. When I came in for a landing, the LG ripped right off the bottom of the fuselage. Turns out, he had only epoxied the LG to the bottom (over the covering no lesss). Its a wonder it hadn't ripped out the week before. Since it had already flown, I hadn't checked the LG mounting. No serious damage, but it was a little embarrassing.

Sometimes being a nice guy to the student (flying the plane without the preflight) is absolutely the wrong thing. Be a little stricter, teach them how to do a proper pre-flight, and they'll thank you many times over in years to come. They'll get fewer flights that day, but they'll have many more flights in the future.

Brad